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using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Reflection;
using System.Web.Util;
namespace System.Web.UI.WebControls {
public class GridViewColumnsGenerator : AutoFieldsGenerator {
public override List<AutoGeneratedField> CreateAutoGeneratedFields(object dataObject, Control control) {
if (!(control is GridView)) {
throw new ArgumentException(SR.GetString(SR.InvalidDefaultAutoFieldGenerator, GetType().FullName, typeof(GridView).FullName));
}
Debug.Assert(dataObject == null || dataObject is PagedDataSource);
PagedDataSource dataSource = dataObject as PagedDataSource;
GridView gridView = control as GridView;
if (dataSource == null) {
// note that we're not throwing an exception in this case, and the calling
// code should be able to handle a null arraylist being returned
return null;
}
List<AutoGeneratedField> generatedFields = new List<AutoGeneratedField>();
PropertyDescriptorCollection propDescs = null;
bool throwException = true;
// try ITypedList first
// A PagedDataSource implements this, but returns null, if the underlying data source
// does not implement it.
propDescs = ((ITypedList)dataSource).GetItemProperties(new PropertyDescriptor[0]);
if (propDescs == null) {
Type sampleItemType = null;
object sampleItem = null;
IEnumerable realDataSource = dataSource.DataSource;
Debug.Assert(realDataSource != null, "Must have a real data source when calling CreateAutoGeneratedColumns");
Type dataSourceType = realDataSource.GetType();
// try for a typed Row property, which should be present on strongly typed collections
PropertyInfo itemProp = dataSourceType.GetProperty("Item", BindingFlags.Public | BindingFlags.Instance, null, null, new Type[] { typeof(int) }, null);
if (itemProp != null) {
sampleItemType = itemProp.PropertyType;
}
if ((sampleItemType == null) || (sampleItemType == typeof(object))) {
// last resort... try to get ahold of the first item by beginning the
// enumeration
IEnumerator e = dataSource.GetEnumerator();
if (e.MoveNext()) {
sampleItem = e.Current;
}
else {
// we don't want to throw an exception if we're bound to an IEnumerable
// data source with no records... we'll simply bail and not show any data
throwException = false;
}
if (sampleItem != null) {
sampleItemType = sampleItem.GetType();
}
// We must store the enumerator regardless of whether we got back an item from it
// because we cannot start the enumeration again, in the case of a DataReader.
// Code in CreateChildControls must deal appropriately for the case where
// there is a stored enumerator, but a null object as the first item.
gridView.StoreEnumerator(e, sampleItem);
}
if ((sampleItem != null) && (sampleItem is ICustomTypeDescriptor)) {
// Get the custom properties of the object
propDescs = TypeDescriptor.GetProperties(sampleItem);
}
else if (sampleItemType != null) {
// directly bindable types: strings, ints etc. get treated specially, since we
// don't care about their properties, but rather we care about them directly
if (ShouldGenerateField(sampleItemType, gridView)) {
AutoGeneratedFieldProperties fieldProps = new AutoGeneratedFieldProperties();
((IStateManager)fieldProps).TrackViewState();
fieldProps.Type = sampleItemType;
fieldProps.Name = "Item";
fieldProps.DataField = AutoGeneratedField.ThisExpression;
AutoGeneratedField field = CreateAutoGeneratedFieldFromFieldProperties(fieldProps);
if (field != null) {
generatedFields.Add(field);
AutoGeneratedFieldProperties.Add(fieldProps);
}
}
else {
// complex type... we get its properties
propDescs = TypeDescriptor.GetProperties(sampleItemType);
}
}
}
else {
if (propDescs.Count == 0) {
// we don't want to throw an exception if we're bound to an ITypedList
// data source with no records... we'll simply bail and not show any data
throwException = false;
}
}
if ((propDescs != null) && (propDescs.Count != 0)) {
string[] dataKeyNames = gridView.DataKeyNames;
int keyNamesLength = dataKeyNames.Length;
string[] dataKeyNamesCaseInsensitive = new string[keyNamesLength];
for (int i = 0; i < keyNamesLength; i++) {
dataKeyNamesCaseInsensitive[i] = dataKeyNames[i].ToLowerInvariant();
}
foreach (PropertyDescriptor pd in propDescs) {
Type propertyType = pd.PropertyType;
if (ShouldGenerateField(propertyType, gridView)) {
string name = pd.Name;
bool isKey = ((IList)dataKeyNamesCaseInsensitive).Contains(name.ToLowerInvariant());
AutoGeneratedFieldProperties fieldProps = new AutoGeneratedFieldProperties();
((IStateManager)fieldProps).TrackViewState();
fieldProps.Name = name;
fieldProps.IsReadOnly = isKey;
fieldProps.Type = propertyType;
fieldProps.DataField = name;
AutoGeneratedField field = CreateAutoGeneratedFieldFromFieldProperties(fieldProps);
if (field != null) {
generatedFields.Add(field);
AutoGeneratedFieldProperties.Add(fieldProps);
}
}
}
}
if ((generatedFields.Count == 0) && throwException) {
// this handles the case where we got back something that either had no
// properties, or all properties were not bindable.
throw new InvalidOperationException(SR.GetString(SR.GridView_NoAutoGenFields, gridView.ID));
}
return generatedFields;
}
private bool ShouldGenerateField(Type propertyType, GridView gridView) {
if (gridView.RenderingCompatibility < VersionUtil.Framework45 && AutoGenerateEnumFields == null) {
//This is for backward compatibility. Before 4.5, auto generating fields used to call into this method
//and if someone has overriden this method to force generation of columns, the scenario should still
//work.
return gridView.IsBindableType(propertyType);
}
else {
//If AutoGenerateEnumFileds is null here, the rendering compatibility must be 4.5
return DataBoundControlHelper.IsBindableType(propertyType, enableEnums: AutoGenerateEnumFields ?? true);
}
}
}
}
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